In certain types of integrated circuits (ICs), changeable negative voltages may be employed. For example, certain types of functional circuits of the IC may require changeable negative voltages to improve their performance. However, conventional transmission circuits for passing a changeable negative voltage to the functional circuit require large area, may employ different type of VT transistors and may require extra bias or clamping voltages. For example, conventional driver circuits include a p-type metal oxide transistor and a n-type metal oxide transistor coupled in series between high and low power sources. Such conventional driver circuits require large layout area especially when the design needs to have deep n-type well.
In addition, the control signal used as an input of the driver circuit is very difficult to define the voltage level. The potential difference between high power source and the negative voltage is much larger than the normal device working range, it creates reliability problems for conventional driver circuits. For example, in a conventional driver circuit for passing the negative changeable voltage has VDD, such as 5V, as the high power source and the negative changeable voltage as its low power source. In such case, the p-type transistor and the n-type transistor both have reliability issues due to the negative voltage low power source. However, if VSS or 0V is used as the high power source, the circuit would not function when the changeable negative voltage is 0V.
The disclosure is directed to a compact and reliable changeable negative voltage transmission circuit for supplying a changeable negative voltage to a functional circuit of an integrated circuit.